Annalee Newitz

Remote gas giant planets Neptune and Uranus could be covered in vast seas of liquid diamond, dotted with solid diamond chunks like icebergs. A new experiment revealed such oceans are plausible, and would explain some oddities about Neptune's magnetic field.

Published recently in Nature Physics, the study is an effort to explain two things: What causes the magnetic poles of Neptune and Uranus to be so far off their geographic poles; and what would cause the planets to have a 10 percent carbon makeup. Diamond seas are the answer, and their experiment suggested that these seas would behave a lot like water oceans.

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Scientists have produced liquid diamond before (you can see a picture of the "z machine" above, which liquifies diamond using electricity and pressure), but mostly for industrial applications. The researchers in this study, however, wondered what would happen to diamond in an ultra-hot, high-pressure atmosphere like Neptune's. Once they had liquified the diamond at extreme pressures, the researchers brought the pressure back up to Neptune levels (about 11 million times Earth's), while bringing the temperature up to the planet's usual 50,000 degrees. As the atmospheric mix stabilized, they discovered that chunks of solid diamond appeared in the liquid, floating atop it like sheets of ice.

Vast seas of diamond could also explain how the giant planet's magnetic fields got warped too, with the magnetic pole as much as 60 degrees off from the geologic one.

If DeBeers owns beaches in South Africa just to protect its diamond mines, imagine what they'll do with this kind of real estate. DeBeers Ocean on Neptune?